Have you ever felt really exhausted during a contest?
For example:Yesterday tourist and Um_nik attended good bye 2019,and also competed with each other post contest and also had the mental stamina to face others?
In a contest,after you solve a very difficult problem,how to garner the zeal to move to an even more difficult problem?
I get mentally exhausted after one single difficult problem,and my brain gets drained.
Practice
I get it,a DIV2 D,may be easy for a red coder,but a DIV1 D/E may pose some challenge to a red coder too,in that case,have you ever felt exhausted?If yes,how do you move on to an even more difficult problem?
You're missing the point.
I think that, because such questions get asked a LOT, and we get always the same answer from reds; "practice" "solve more" etc.. that we don't really understand/believe it anymore.
By practice, you will be able to move on from a difficult problem to a more difficult problem with your morale and your brain intact.
By trying to move to the 3rd problem many times, you will eventually succeed and get there.
There is no other answer, none.
It really makes sense if you think about it. Recall any video game you played or any sport you practiced and ask yourself, how have I improved in it??
I'm just saying that practice will make you able to focus for a longer period of time. A brain is a muscle, train it and it will be stronger.
Anatomically brain is not a muscle.
I'm pretty sure there is some physical aspect; being fit and healthy gives you much more stamina (you can see this in any competition environment (like chess), the best players have good physical fitness).
Additional note on top of default (and correct, I believe) "practice" suggestion: keep in mind that most top contestants have significant ICPC experience, and even a single season of reasonable preparation could potentially mean 100 or more team contests.